Momoko, Kaeru no Uta ga Kikoeru yo., Happy Birthday: Inochi Kagayaku Toki Recommendations
Tell about difficult vital problems of children, about cruelty at school and in a family.
The animation and art style are extremely similar because the same staff worked on both movies. Both movies center around children with special needs and how loving and special they can be to the people around them. Both end in sad but beautiful ways. You will enjoy one if you enjoyed the other.
Both tell wholesome stories of lacking acceptance, admitting mistakes, forgiveness, grief and loss.
They have similar vibes and were produced by Magic Bus, the same studio that made Ginga Eiyuu Densetsu.